WO2015091944A2

WO2015091944A2 - Method and apparatus for scattering fibers, such as chips

Info

Publication number: WO2015091944A2
Application number: PCT/EP2014/078729
Authority: WO
Inventors: Markku Erämaja
Original assignee: Dieffenbacher GmbH Maschinen- und Anlagenbau
Priority date: 2013-12-20
Filing date: 2014-12-19
Publication date: 2015-06-25
Also published as: FI125434B; WO2015091944A3; CN204546717U

Abstract

Method for scattering fibers, such as chips, in surface chip scattering, in which method chips are scattered to form a chip mat (9) on a moving belt conveyor (10) or corresponding, in which method two sets of scattering rollers (1, 2) are used for the scattering, both sets being formed of rollers arranged side by side and being at different heights and being arranged above the belt conveyor (10). The invention is implemented in such a way that the roller sets (1, 2) are arranged consecutively with the upper roller set (1 ) being the first in the direction of travel of a chip, in which case a gas flow (5) is arranged to below the upper roller set (1) by arranging a gas blowing head (14) between the tail end of the upper roller set (1) and the start end of the lower roller set (2). The object of the invention is also an apparatus for implementing the method.

Description

METHOD AND APPARATUS FOR SCATTERING FIBERS, SUCH AS CHIPS

The object of the present invention is a method for scattering fibers, such as chips, in surface chip scattering, in which method chips are scattered to form a chip mat on a moving belt conveyor or corresponding, in which method two sets of scattering rollers are used for the scattering, both sets being formed of rollers arranged side by side and being at different heights and being arranged above the belt conveyor. Additionally, the object of the invention is an apparatus for implementing the method.

The purpose of scattering is to bring about the desired type of chip mat before pressing it into chipboard. The aim in a chip mat is e.g. to get the finer fraction onto the surface and the coarser fraction into the middle.

Mechanical roller scattering, in which there is one scattering roller set and with which good scattering accuracy can be achieved, i.e. little variation in the square meter weight of the scattered chip mat, is known in the art from e.g. FI patent 90746.

FI patent application 20060437 and FI patent 122575 are, for their part, known to use a gas flow for improving the fractionating of chips in roller scattering, in which one scattering roller set is in use, the rollers of which are on the same level.

The thin surfacing papers of chipboard that are used nowadays require greater and greater density of the ground surface of the chipboard, i.e. the surface must be formed from a fine and fibrous chip fraction. In addition, the surface must be free of large chip particles of over 0.5 mm.

Known in the art therefore are apparatuses based both on wind scattering and on roller scattering. There are no serious problems in a wind scatterer when the scatterer is in good condition in all respects, but the difficult adjustability of a wind scatterer causes problems, resulting in surface quality problems and production losses. In addition, a wind scatterer easily becomes dirty, which causes many cleaning standstills and more production losses. A wind scatterer also has a rather high energy requirement and they are large in size.

A problem with a roller scatterer is obtaining by means of a roller set and chamber wind a sufficient fine and fibrous fraction for the grinding layer. On high-capacity lines the conveying of a fibrous fraction to the grinding layer is impossible, because the roller scatterer conveys almost all the fiber to the downstream end, from where it is impossible to get it by means of wind to the start end through the thick multiple chip curtain. In addition, overlarge (over 0.5 mm) chip particles escape through the roll gaps of the start end and these chips are visible on the surface of the board after grinding.

In prior-art roller scatterers, in which a gas flow is used as an aid for improving the fractionation of the chips, a relatively large flow of gas is directed into the whole quantity of chips being scattered and all the chips are dropped into the same relatively tall chamber for fractionating in the gas flow (such as is presented in e.g. FI patent 122575). However, typically only less than half of the surface chips would need to be fractionated in order to achieve the aforementioned ground fine surface of the chipboard. It is not necessary to fractionate the remainder of the coarser surface chip portion because it settles to become an intermediate layer below the ground surface e.g. between the fractionated, fine surface layer and the middle chip layer that is generally scattered separately. In order to minimize variation in the total square meter weight of the scattered chip mat, it would be advantageous if e.g. the coarse portion (which is typically thus over one-half of the total amount of surface chips) could be scattered precisely by using a scattering chamber that is a shallow as possible and as low a gas flow speed as possible in the chamber in question.

The aim of the present invention is to achieve a method that can achieve high scattering accuracy, as a result of the leveling effect of the roller set, the relatively low suction air speed, and the relatively shallow drop height below the roller set, and that can simultaneously also achieve an advantageous chip fractionating result requiring a tall scattering chamber and relatively high speed of the gas flow.

The method according to the invention is characterized in that the roller sets are arranged consecutively with the upper roller set being the first in the direction of travel of a chip, in which case a gas flow is arranged to below the upper roller set by arranging a gas blowing head between the tail end of the upper roller set and the start end of the lower roller set.

One preferred embodiment of the method according to the invention is characterized in that a gas flow is also arranged to below the lower roller set, which gas flow is in essentially the same direction as the gas flow below the upper roller set.

Another preferred embodiment of the method according to the invention is characterized in that the speeds of the gas flows are arranged adjustably.

Additionally the purpose of the invention is to achieve an apparatus for implementing the method, which apparatus is characterized in that the upper roller set and the lower roller set are arranged consecutively in such a way that the upper roller set is the first in the direction of travel of a chip, and in that a gas flow is arranged to below the upper roller set, which is at least partly implemented with a gas blowing head arranged between the tail end of the upper roller set and the start end of the lower roller set.

One preferred embodiment of the apparatus according to the invention is characterized in that a fan is connected by means of piping to the gas blowing head, via which fan gas is blown into the gas blowing head.

Another preferred embodiment of the apparatus according to the invention is characterized in that a means is arranged between the tail end of the upper roller set and the start end of the lower roller set for conveying chips in a controlled manner from the upper to the lower roller set.

With the method and apparatus based on mechanical roller scattering according to the invention, therefore, it is possible to implement fractionating scattering and also, owing to the shallow drop height as well as the low speed of the gas flow to be used in the shallow drop chamber in question, high scattering accuracy. In the invention the good properties of wind scattering and of roller scattering are combined. By means of the invention sufficient fine and fibrous chips are obtained for the grinding layer. The adjustments needed for optimizing scattering accuracy in the invention are easy to implement and on the whole there is little need for adjustment. In the apparatus according to the invention also dirt accretion hampering operation does not occur.

In the following, the invention will be described in more detail by the aid of some preferred embodiments with reference to the attached drawings, wherein
Fig. 1 presents an apparatus according to the invention for scattering chips.
Fig. 2 presents the gas blowing head of Fig. 1.
Fig. 3 presents apparatus according to one preferred embodiment of the invention for scattering chips.
Fig. 4 presents an apparatus according to one preferred embodiment for conveying chips in a controlled manner from the upper to the lower roller set, as well as the gas blowing head installed between these roller sets.
Fig. 5 presents an apparatus according to a second preferred embodiment for conveying chips in a controlled manner from the upper to the lower roller set, as well as the gas blowing head installed between these roller sets.
Fig. 6 presents an apparatus according to yet another preferred embodiment for conveying chips in a controlled manner from the upper to the lower roller set, as well as the gas blowing head installed between these roller sets.
Figs. 7-9 present in more detail the embodiment according to Fig. 6.

Fig. 1 thus presents a chip scattering apparatus according to the invention. The chips to be scattered are fed from the scattering bunker 3, in a manner that is per se known in the art, to a first, i.e. an upper, roller set 1, which is formed from rollers that are side by side, and from where the chips drop into a relatively tall fractionating chamber 4, in which they are sorted effectively by means of a gas flow 5. The speed of the gas flow can, if necessary, be adjusted. The fractionating chamber 4 is formed between the upper roller set 1 and the scattering belt conveyor 10.

In the gas flow 5 the finer, light, dusty and thinnest fibrous portions 6 fly farthest to improve the surface quality of the final product, whereas the heavier and coarser, typically grainy fractions 7 displace only a little or not at all and remain inside the final product below the fine surface. The chips fractionated in the manner described above drop to become the finer part of the chip mat 9 on the scattering belt conveyor 10. The chip portion that does not need to be fractionated is transported in a controlled manner to the lower roller set 2. From the roll gaps between the rollers of the roller set 2 these coarser chips drop preferably via a chamber 8 arranged to be as shallow as possible to become the coarser part of the chip mat 9 on the scattering belt conveyor 10.

A gas flow 12 is also arranged into the shallow chamber 8, which is formed between the lower roller set 2 and the scattering belt conveyor 10. To prevent turbulence impairing the scattering accuracy this gas flow 12 of the shallow chamber 8 can, if necessary, be adjusted e.g. by means of a flap 13 so as to be sufficiently low and free of turbulence. Overlarge particles unsuited to the final product go over the roller set 2 and they are removed from the process in a manner known in the art on a transverse conveyor 11.

The roller clearances and rotation speeds of the rollers of the

roller sets

1 and 2 can, if necessary, be adjusted and the depths of the surface patterning of the rollers can be varied with methods known in the art for achieving the desired end result.

For further improving the scattering accuracy, plate-like elements 16 preventing turbulence of the gas flow 5 (as known from FI patent 122575) can also be added to the chamber 4.

The gas flows 5 and 12 are brought about by means of suction arranged via the pipe 25 as well as by means of the gas blowing head 14 and the fans 15. A solution according to one embodiment (Fig. 1) of the gas blowing head is presented in Fig. 2, which is a view in the direction A of Fig. 1. In this, therefore, gas is blown by means of fans 15 into the gas blowing head along two different pipes, as presented in Fig. 2, from which gas blowing head the gas discharges via a perforated front plate in the manner presented by the arrows (Fig. 1).

Fig. 3 presents a scattering station for a chip mat, in which scattering station the lower surface layer 17 and the upper surface layer 18 are scattered with the method and

apparatuses

21 and 22 according to the invention. Generally also a middle layer 19 is scattered, with either one or more middle chip scattering machines 20, between these layers. For further improving scattering accuracy there is, when producing chip mats of different thicknesses, at least a scattering device 22 of the top surface layer, said device arranged to be movable in the vertical direction with a lifting system 24, with which the free drop height at any given time of the chamber 8 that is under the lower roller set 2 can be optimized/minimized.

Figs. 4-6 present three different apparatuses, with which chips can be conveyed in a controlled manner from the upper to the lower roller set, as well as the gas blowing heads installed between these roller sets. In Fig. 4 a dropping roller 23 is installed on the tail end of the upper roller set 1, which dropping roller can be e.g. a similar brush roller or corresponding, to that used for dropping chips in a controlled manner from the bunker to the upper roller set. In Fig. 5 the dropping roller 23 is replaced with a belt conveyor 26. Fig. 6 presents an embodiment wherein the gas blowing head is made from a rotating mesh or from a perforated plate roller 27. As it rotates the roller conveys chips from the upper roller set 1 to the lower roller set 2 and at the same time blowing is arranged in the manner indicated by arrows to below the upper roller set 1.

The embodiment presented in Fig. 6 is presented in more detail in Figs. 7-9. From Fig. 8 a non-rotating perforated pipe 28 is seen, through which gas is blown. A rotating mesh roller or perforated plate roller 27 is mounted via bearings on the perforated pipe 28. The reference number 29 presents a non-rotating prevention plate, which directs the blowing in the manner indicated by the arrows 30.

In Fig. 9 the structure is presented from a different direction. The mesh roller and its bearing system are visible in it. The mesh roller is rotated e.g. by means of a belt drive 31. It is seen from Fig. 9 that gas is brought to inside the mesh roller from both ends.

It is obvious to the person skilled in the art that the invention is not limited to the embodiments described above, but that it can be varied within the scope of the claims presented below.

The characteristic features possibly presented in the description in conjunction with other characteristic features can if necessary be used separately to each other.

Claims

Method for scattering fibers, such as chips, in surface chip scattering, in which method chips are scattered to form a chip mat (9) on a moving belt conveyor (10) or corresponding, in which method two sets of scattering rollers (1, 2) are used for the scattering, both sets being formed of rollers arranged side by side and being at different heights and being arranged above the belt conveyor (10), characterized in that the roller sets (1, 2) are arranged consecutively with the upper roller set (1) being the first in the direction of travel of a chip, in which case a gas flow (5) is arranged to below the upper roller set (1) by arranging a gas blowing head (14) between the tail end of the upper roller set (1) and the start end of the lower roller set (2).
Method according to claim 1, characterized in that a gas flow (12) is also arranged to below the lower roller set (2), which gas flow is in essentially the same direction as the gas flow (5) that is below the upper roller set (1).
Method according to claim 2, characterized in that the speeds of the gas flows (5, 12) are arranged adjustably.
Apparatus for scattering fibers, such as chips, in surface chip scattering, which apparatus comprises a scattering bunker (3), an upper scattering roller set (1) arranged below it, which scattering roller set is formed from rollers side by side, and also a lower scattering roller set (2), which is formed from rollers side by side, and also a belt conveyor (10) arranged to be lowermost, on which belt conveyor a chip mat (9) forms, characterized in that the upper roller set (1) and the lower roller set (2) are arranged consecutively in such a way that the upper roller set (1) is the first in the direction of travel of a chip, and in that a gas flow (5) is arranged to below the upper roller set, which is at least partly implemented with a gas blowing head (14) arranged between the tail end of the upper roller set (1) and the start end of the lower roller set (2).
Apparatus according to claim 4, characterized in that a fan (15) is connected by means of piping to the gas blowing head (14), via which fan gas is blown into the gas blowing head.
Apparatus according to claim 4 or 5, characterized in that a means (23, 26, 27) is arranged between the tail end of the upper roller set (1) and the start end of the lower roller set (2) for conveying chips in a controlled manner from the upper to the lower roller set.
Apparatus according to claim 6, characterized in that the means is a rotating dropping roller (23), such as a brush roller.
Apparatus according to claim 6, characterized in that the means is a belt conveyor (26).
Apparatus according to claim 6, characterized in that the apparatus is a rotating mesh roller (27), which is integrated into the gas blowing head.
Apparatus according to any of claims 4-9, characterized in that plate-type elements (16) preventing turbulence of the gas flow are arranged below the upper roller set (1, 2).